We didn't need to consult an 'expert' for this one...
Blunt: A polite, but honest, "I don't think this is going to work out."
Crazy: Tell the same anecdote five times in a row. Your date should wind up the evening quick sticks. (Speed it up by making the anecdote about your latest purchase/boyfriend/venereal disease.)
Sneaky: The ol' climb out the bathroom window move is about as sneaky as they come. And a little unnecessary, we might add.